Trigonometric identifier



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. N. DE TURN TRIGOHOMETRIC IDENTIFIER' Filed Fab. 21, 1940 uw of G Law of mes Fawkes .i L avmf ab: cas/1 2 Sheets-Sham. 2

Patented Mar. 11, 1941 Unire smeg@ Application February 2l 3 Claims;

This invention relates to a device constituting an indicator capable of being readily adjusted for giving identities to functions of angles in the study of trigonometry.

More particularly, it is an aim of this invention to provide a mechanism especially designed and adapted as an aid to students in the study of trigonometry and higher mathematics for quickly identifying the functions of angles by Ameans of simple manipulation of the mechanism to thereby avoid the loss of time resulting in locating the same information in teXt books.

Still another aim of the invention is to provide a mechanism of simple construction capable of f being economically manufactured and sold, and

which may be readily operated for indicating the functions of angles.

Still another aim of the invention is to provide a mechanism of the character, as heretofore explained, on the reverse side of the base portion of which is adapted to be provided indicia including the law of sines, cosines, and tangente and a number of helpful equantities.

Other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, which illustrate a preferred embodiment thereof, and wherein:

Figure l is a top plan View of the device,

Figure 2 is a longitudinal vertical sectional View taken substantially along the plane of the line 2-2 of Figure 1,

Figure 3 is a bottom plan View of the device,

Figure i is a top plan view of the upper disk, and

Figure 5 is a similar view of the lower disk.

Referring more particularly to the drawings, wherein like reference characters designate like or corresponding parts throughout the different views, Iii designates generally the indicator which includes a base member ll and disks l2 and I3. Disks i2 and I3 are superimposed on the base Il and rotatably connected thereto and to one another by a ferrule or other fastening It with the disk I3 above the disk IE. Disks I2 and It are oi substantially the same sise, while the base il is substantially larger than the disks and may be of any desired shape.

The base I I, as best seen in Figures l. and 2, on its exposed upper surface is provided with four equally spaced component parts of one set of in dicia, designated generally I5. The parts of the indicia I5 each include a corresponding calibration line I6 which extends radially from the peripheries of the disks I2 and I3, which lines 1940, Serial1 No. 32%,Z`l3

(Cl. S5-J74) are marked respectively sin, cot, tan and cos, being abbreviations of sine, cotangent, tangent and cosine, respectively. The base II is also provided with a second series of indicia, designated generally Il and comprising six parts which are equally spaced relatively to each other and which are disposed between two of the calibration lines Iii, of the indicia I5, as illustrated, between the lines designated sin and cot However, the series of indicia Il could obviously be disposed between other pairs of the calibration lines IIS, if desired. The indicia Il includes six equally spaced calibration lines It which project radially from the peripheries of the disks I2 and I3 and which are marked respectively, reading in a clockwise direction, Reciprocls, (9o-|-), (1/2) n (Z) n n and n(+y) n As best seen in Figure 5, the lower disk l2 is provided with a tapered extension I9 which projects from a portion of its periphery to form a pointer and the upper surface of the disk I2 is blocked off by means of two spaced concentric circles and a plurality of radially disposed lines extending between said circles to form thereon twenty-four closed spaces 2d each of which con tains certain indicia 2l.

The upper disk I3 is provided with a similar pointer 22 which is preferably distinctively marked to thereby distinguish the pointers I9 and 22. Disk I3 also includes an opening 23 shaped, sized and positioned to correspond with the spaces 2l! so that by rotating the disk I3, relatively to the disk I2, opening 23 can be disposed over any one of the twenty-four spaces 26 to expose the indicia 2| contained therein. 35

As best seen in Figure 3, the back of the base member II is preferably provided with printed matter including the law of sines, the law of cosines, the law of tangents and a number of quantities, designated generally 213.

As heretofore stated, the indicator IIJ is designed for use in giving identities to functions of angles in the study of trigonometry. The four parts of the set of indicia I5 constitute the four major functions and are spaced 90 apart, while the six parts of the series of indicia I'I constitute the six minor functions which are spaced within the 90 space between two parts of the indicia I5. The letters and y designate the word angle The base member II, disk I2 and disk I3 are preferably formed of corresponding material and it may be stated that any suitable material may be used such as cardboard, paper, Celluloid, thin metal or any other suitable material on which the indicia heretofore described Cil may be inscribed, preferably a material that will be durable.

The operation of the indicator IIJ is as follows: assuming that the operator desires to ascertain the cosine of twice an angle, the disk I2 is turned until its pointer I9 is centered over the calibration line I 6 marked cos, after which the disk I3 is turned to center the pointer 22 over the calibration line I8 designated (2). The indicia 2I which is then exposed by the opening 23 will then read 2 cos2 -l. This indicia 2| is the function of the cosine of twice an angle. Obviously other functions of angles may be similarly found by similar manipulations of the indicator I0 in each instance by adjusting the disk I2 so that the pointer I9 is on the major function and the disk I3 so that its pointer 22 is on the minor function.

Various modifications and changes in the construction and arrangement of the parts forming the invention are contemplated and may obviously be resorted to as only a preferred embodiment thereof has been disclosed.

I claim as my invention:

l. A device of the class described comprising a base member, a pair of disks superimposed thereon, means for rotatably connecting said disks to said base, said base being provided with indicia on its upper side including four parts comprising the four major functions of an angle disposed in equally spaced apart relationship to each other on the exposed portion of said upper surface, and indicia arranged between two adjacent parts of the aforementioned indicia and including six parts comprising six minor functions of angles,

said lower disk being provided with an arrowhead projecting from a portion of its periphery and forming a pointer t0 be positioned selectively on the parts of said first mentioned indicia, the upper surface of said lower disk being inscribed with indicia comprising a plurality of functions or identities of angles, and said upper disk being provided with an arrow-head projecting from its periphery and forming a pointer to be positioned selectively on the last mentioned indicia of said base, said last mentioned disk being provided with an elongated radially extending opening disposed in substantially diametrically opposed relationship to its pointer for reading the correct or necessary function or identity, forming a part of the indicia on said lower disk and exposed by the opening in the upper disk.

2. A trigonometric identifier comprising a base member, two disks pointed one on top of the other and on said base member, means for rotatably mounting the disks relatively to each other and to said base member, said disks each being provided with an arrowhead projecting from a portion of its periphery and forming a pointer, said base member being substantially larger than said disks, the upper surfaceof the exposed portion of said base member being provided with sets of indicia over which the pointers of the disks are selectively positioned for adjusting the disks relatively to each other for indicating the problem, the upper surface of the lower disk being provided with indicia comprising solutions to the problems, and said upper disk being provided with an elongated radially extending opening disposed in substantially diametrically opposed relationship to the pointer of the upper disk through which the correct solution can be read.

3. A trigonometric identier comprising a base member, a pair of disks superposed on said base member, one above the other, means for rotatably connecting said disks to each other and to said base member, tapered extensions on portions of the peripheries of said disks forming pointers, said upper disk being provided with an elongated radially extending opening disposed substantially in diametrically opposed relationship to the pointer of the upper disk for exposing a portion of the lower disk, said base member being substantially larger than said disks and having a set of indicia on the exposed portion of its upper surface including four equally spaced parts for designating four diierent positions of the lower disk as indicated by its pointer, said base member also including a second set of indicia including six equally spaced parts for designating various positions of the upper disk as indicated by its pointer, the parts of the indicia of the second set being all disposed between two adjacent parts of the indicia of the rst set, and the upper surface of the lower disk being provided with indicia of twenty-four correspondingly spaced parts, each associated with one of the twenty-four different positions in which the two disks may be positioned relatively to each other and constituting a solution of a problem as indicated by the positioning of the disks relatively to the indicia of the base member.

WILLIAM NELSON DE TURK. 

